1. Field of the Invention
This invention relates to a process for dewaxing a ceramic molded body, and more particularly to a process for dewaxing an injection molded body placed upon a porous ceramic.
2. Description of the Prior Art
Silicon ceramics such as silicon nitride, silicon carbide, sialon and the like; alumina ceramics, zirconia ceramics and so on are stable at elevated temperatures, as compared with metallic materials, and are hardly subjected to oxidation corrosion and creep deformation, so that they are heavily studied to be utilized as engine parts.
In order to mold turbine rotors and the like having complicated shapes among the engine parts, an injection molding process is preferable and is widely utilized. However, such an injection molding process has the greatest fault in the dewaxing step. For this reason, there are proposed various processes for producing a thick molded body without cracking during dewaxing.
There has been generally known placing a molded body after injection molding on a base plate made of an alumina ceramic or the like and the temperature thereof is slowly raised in an electric furnace to gradually remove a binder from the molded body. However, when a wax-series binder is used as the binder, cracks occur from the bottom face of the molded body which contacts with the base plate, which frequently results in poor dewaxing.